Rotary engine with interengaging rotating members and reversing valve

ABSTRACT

A Rankine cycle rotary engine and gas flow control valve mechanism used therewith. A housing of the engine forms a pair of cylindrical cavities in which primary and secondary rotors are mounted for rotation about spaced, parallel axes. Three outwardly projecting lobes on the primary rotor intermesh with three concaval recesses on the secondary rotor, and a timing gear train is provided to turn the secondary rotor in opposite and equal angular rotation with the primary rotor. Gas under pressure is directed through a distributor chamber to a flow control valve sleeve mounted for axial sliding movement concentrically within the primary rotor. Pairs of radially extending distributor passageways are formed in each of the lobes to direct gas from the valve into successive expansion chambers formed between the intermeshing lobes and recesses. The valve sleeve is formed with a pair of axially spaced apart flow control ports. The control ports are bounded by pairs of admission and cutoff edges which diverge apart in opposite axial directions. Means is provided to axially position the valve sleeve for throttling by varying the angular sector of the control port opening which is in register with the distributor passageways, and further to carry either port into register with these passageways for forward, braking or reverse engine operation. Residual gas from secondary rotor recesses which have disengaged from their associated primary rotor lobes is directed through secondary passages to expand and act against the primary rotor.

United States Patent 191 Roth et al.

' 451 May 21, 1974 ROTARY ENGINE WITH INTERENGAGING ROTATING MEMBERS ANDREVERSING vALvE' inventors: Larry L. Roth, 39 Palm Ave.,

Millbrae, Calif. 94030; Joseph Liston, 900 Robinson Ave., WestLafayette, Ind. 47906 [22] Filed: Dec. 29, 1972 [21] Appl. No.: 319,841

[52] US. Cl 418/32, 418/185, 418/188,

, '418/l91,251/205 [51] Int. Cl......F0lc1/08, F04c 17/04, FOlc 21/16[58] Field of Search 418/185, 32, 188, 191, 418/227; 251/205, 206, 209

[56] References Cited UNITED STATES PATENTS 54,006 4/1866 Norton 418/191865,964 9/1907 Bleecker 418/191 811,747 2/1906 Rowe et a1 418/191902,225 10/1908 Friend 418/191 2,158,737- 5/1939 Wunsch 1,269,735 6/1918Ogden...

2,177,976 10/1939 Brauer 3,191,541 6/1965 Brown 418/32 FOREIGN PATENTSOR APPLICATIONS 326,370 9/1920 Germany 418/183 France 418/187 PrimaryExaminer-Carlton R. Croyle Assistant Examiner-John J. Vrablik 7Attorney, ige nt, or Firm -Flehr l-lohbach Test Albritton & Herbert [57] ABSTRACT A Rankine cycle rotary engine and gas flow control valvemechanism used therewith. A housing of the engine forms a pair ofcylindrical cavities in which primary and secondary rotors are mountedfor rotation about spaced, parallel axes. Three outwardly projectinglobes on the primary rotor intermesh with three concaval recesses on thesecondary rotor, and a timing gear train is provided to turn thesecondary rotor in opposite and equal angular rotation with the primaryrotor. Gas under pressure is directed through a distributor chamber to aflow control valve sleeve mounted for axial sliding movementconcentrically within the primary rotor. Pairs of radially extendingdistributor passageways are formed in each of the lobes to direct gasfrom the valve into successive expansion chambers formed between theintermeshing lobes and recesses. The valve sleeve is formed with a pairof axially spaced apart flow control ports. The control ports arebounded by pairs of admission and cutoff edges which diverge apart inopposite axial directions. Means is provided to axially position thevalve sleeve for throttling by varying the angular sector of the controlport opening which is in register with the distributor pass; 4 ntawiq fi1 ROTARY ENGINE WITH INTERENGAGING ROTATING MEMBERS AND REVERSING VALVEBACKGROUND OF THE INVENTION This invention relates in general to rotaryengines, and in particular relates torotary engines which operate on aRankine cycle. The invention also pertains to flow control valves usedwith such engines.

There has been an increasing recognition of the many inherentdisadvantages and limitations of. internal combustion engines, such asthose operating on Otto or Diesel cycles, as well as the disadvantagesand limitation of reciprocating engines which operate on either internalor external combustion cycling. A'disadvantage of considerableimportance in internal combustion engines is the inability toelfectivelyreduce harmful exhaust from the engine, with the concomitant increase inair pollution. It is known that external combustion engines such asthose operating on the Rankine cycle and using a working fluid'such assteam can. reduce or eliminate many of these disadvantages. Combustionmay be more effectively controlled: in a Rankine cycle system to insuremore complete fuel burning, and without producing. large amounts ofharmful by-products such as carbon monoxide, unburned hydrocarbons andoxides of nitrogen.

It is also widely recognized that rotary. engine designs, whetheroperating on Rankine or Otto cycle principles, provide importantadvantages over reciprocating engines. Generally rotary engines can bebalanced to run at relatively high rotationspeedswithout the undesirablevibrations, high stresses and high inertia loads whichotherwise occurfrom the rapid acceleration and deceleration of moving parts in areciprocating engine.

OBJECTS AND SUMMARY OF THE INVENTION It is a general object of theinvention to provide an improved rotaryengine adapted for operating on aRankine cycle to producemechanical :work from a source of gas underpressure (e.g. steam or the like).

Another object of the invention is to provide a rotary engine of thecharacter described which achieves the many advantages of Rankine cycleoperation such as reduced exhaust emission and more complete fuelburning through a structure having a relatively high power-to-weightratio, a favorable torque curve, and with engine elements which undergopure rotary motion that is productive of relatively smooth andvibration-free operation. 1

Another object is to provide a rotary engine of the character describedwhich incorporates a relatively few number of moving parts, isrelatively inexpensive in construction and operation, and is relativelysimple to repair and maintain. I

Another object is to provide a valve mechanism which controls gas flowto an engine of the character described in a manner affording selectiveforward, re-

verse, braking and throttling operation under influence of a singlecontrol element.

The foregoing and additional objects and features of the invention areprovided in the invention by a rotary engine having primary andsecondary rotors mounted for rotation within a housing about parallel,spacedapart axes. A plurality of lobes are formed on the primary rotorfor meshing engagement with corresponding recesses formed on thesecondary rotor. A gas under pressure developed from an externalcombustion process in a Rankine cycle system is directed by flow controlmeans into expansion chambers which are successively formed between theintermeshing lobes and recesses. The resultant of forces from the gasseswithin the expansion chambers are balanced on the secondary rotor, butproduce a torque force acting eceentrically on the primary rotor. Thistorque force turns the primary rotor about its axis to producemechanical work and at the same time drives a timing gear train forturning the secondary rotor in equal and opposite angular rotation withthe primary rotor. The flow control means includes a valve sleeveadapted to control both forward and reverse engine rotation, braking,and engine throttling by the single function of axial adjustment of thesleeve. The valve sleeve includes forward and reverse ports formed ataxially spaced positions with oppositely diverging admission and cut-offedges arranged so that varied axial positions of the sleeve movesvariable angular sectors of port openings into register with paireddistributor passageways leading through the lobes and opening into theexpansion chambers. Provision is made for balancing the pressure forcesacting on the valve sleeve so that the force required for axial shiftingof the sleeve is relatively small. Secondary passageways are formed inthe housing to direct residual gases from the recesses which havedisengaged from their associated lobes so as to act upon and developadditional torque against the primary ro- 1101'.

BRIEF DESCRIPTION OF THE DRAWINGS line 3-3 of FIG. 1; and

FIG. 4 is an elevational view of a component control valve member forthe engine of FIG. ll.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings FIG.1 illustrates generally at 10 a preferred embodiment of therotary'engine of the present invention. The rotary engine 10 isspecially adapted for use in a Rankine cycle system where a workingfluid (e.g. steam or a Freon gas) is generated by means of thecombustion of a fuel in an external combustion chamber connected ineither open or closed fluid flow circuitry. In a closed circuitarrangement suitable condensers, pumps, boilers, piping and otherequipment, not shown, would be employed for condensing and recovery ofthe expanded gases exhausting from the engine 10. Such equipment isbroadly conventional and is not shown herein as it forms no part of thepresent invention.

Rotary engines 10 includes a housing 11 comprising housing half sections12, 13 bolted together about their outer periphery by suitable meanssuch as the circle of bolts 14. The bases of the two housing sectionsdefine a flanged support adapted for anchoring by suitable means such asbolts to a foundation or engine-support. The interior volume between thetwo housing sections defines an upper cylindrical walled cavity 16 and alower cylindrical walled cavity 17 overlapping with and of a greaterdiameter than the upper cavity.

A primary rotor 18 is mounted within lower cavity 17 for rotation abouta first axis 19 extending longitudinally of the engine. A plurality,preferably three, of radially outwardly extending lobes 21, 22 and 23are formed on the primary rotor at equally spaced apart circumferentialpositions. The outer peripheral surface of each lobe defines a sectionof a cylindrical surface adapted to move inclose-fitting, sealingrelationship with the inner surface of lower cavity 17. The axial endfaces of the primary rotor are in close-fitting rotary sealing contactwith the opposing housing faces forming the lower cavity. As bestillustrated in FIG. 3 annular cylindrical supports 24, 25 extend axiallyfrom either end of the primary rotor, and these supports are joumaledfor rotation within sleeve bearings 27, 28. The right-hand sleevebearing 27 is carried within a cylindrical support 29 formed integrallywith and extending outwardly from housing section 12, and the oppositesleeve bearing 28 is carried within a cylindrical support 30 formedintegrally with and extending outwardly from an end cover 32 secured tohousing section 13 by suitable means such as the circle of machinescrews 33. The primary rotor 18 is connected to the desired end useapplication or power shaft, not shown, by suitable means such as thedrive gear 34 keyed to an output shaft 36 which is formed integrallywith a circular end plate 37 mounted at the end of support 25.

The interior volume which lies concentrically within the primary rotorforms a gas distributor chamber 38. Gas is directed to this distributorchamber from a suitable supply conduit, not shown, connected at one endwith the source of gas under pressure (e.g. a steam generator or boiler)and connected at its other end with flanged inlet port 39 which feedsgas into an annular channel 41 formed in sleeve bearing 27.-A pluralityof radially extending circumferentially spaced openings 42 are formedthrough the end support 24 of the primary rotor, and these openings turnwith the rotor in register with annular channel 41 to direct inlet gasinto the distributor chamber. A circular end plate 43 is secured withina recessed seat of end support 24 to define the outer end wall of thedistributor chamber.

A secondary rotor 44 is mounted within upper cavity 16 on a shaft 46 forrotation about an axis 47 parallel with and spaced vertically above theprimary rotor axis 19. A plurality of radially inwardly projectingconcaval lunettes or recesses 48, 49, 50, equal in number to the numberof primary rotor lobes, are formed in the secondary rotor. The outerperipheral surfaces or rim portions 52 of the secondary rotor which liesbetween the recesses are sized for close-fitting rotary movement withincavity 16 to provide a fluid seal for the gasses within the working orexpansion chambers 53 which are successively fonned between theintenneshing lobes and recesses. The axial end faces of the secondaryrotor are in close-fitting rotary sealing contact with the opposinghousing faces forming the upper cavity. Shaft 46 for the secondary rotoris rotatably journaled at one end by sleeve bearing 54 within a boss 55formed integrally with housing section 12, and is rotatably joumaled atits other end by sleeve bearing 54 within a boss 56 formed integrallywith end cover 32.

Timing means is provided for turning secondary rotor 44 in one-to-onesynchronous driving relationship with primary rotor 18. This timingmeans preferably comprises a gear train including a drive gear 57mounted about and keyed for rotation with the cylindrical support 25 ofthe primary rotor. A driven gear 58 is provided with the same number ofteeth as the drive gear,

and thedriven gear is keyed for rotation with secondary rotor shaft 46.The two gears 57, 58 intermesh to turn the secondary rotor in equal andopposite angular relationship with the primary rotor for maintainingintermeshing engagement of the respective lobes and recesses.

The configuration of the primary and secondary rotors together withtheir respective cylindrical cavities are symmetrical so that the engineis adaptable for forward and reverse rotational operation. Theperipheral surface of the primary rotor lobes and secondary rotorrecesses define substantially gear tooth profiles so that the opposedsurface portions of interrneshing lobes and recesses are in close-spacedcontact for sealing the gases within the expansion chambers. The primaryand secondary rotors and their respective axes are sized and spacedapart with predetermined dimensions so that, with the two rotors intheir dead-center positions as illustrated in FIG. 1, the expansionchamber '53 defines a crescent configuration in section between theouter surface of the lobe 21 and the opposed root portion of theassociated secondary rotor recess 49. This expansion chamber has anaxial width equal to the axial width of the two rotors. With the rotorsturned away from the dead-center position, e.g. to the positionillustrated in FIG. 2, the resultant force from pressurized gas fromwithin the expansion chamber acts eccentrically to and imparts a drivingtorque against the primary rotor. It will be noted that, with the lobesand recesses in engagement, the pressure forces within the expansionchamber act against projected areas of the secondary rotor which areequal on either side of its axis of rotation so that there is no netdriving torque imparted to the secondary rotor. Suitable means may beprovided to drive the primary rotary past its dead-center positionshould it stop in this position. For example, one or more pairs ofadditional primary and secondary rotors may be drivingly connected outof phase with the illustrated rotors, or a starting motor and flywheelarrangement, not shown, may be coupled with output shaft 36.

Means for controlling the flow of pressurized gas into the successiveexpansion chambers is provided. This flow control means includes pairsof substantially radially extending distributor passageways 59, 60formed in each of the three lobes 21-23. The passageways for each lobediverge outwardly from a common inlet port 62 into distributor chamber38, with the passageways leading to outlet ports 63, 64 opening throughthe outer peripheral surface of respective lobes for communication withthe expansion chambers 53. The outlet ports are circumferentiallyspaced-apart to extend delayed cutoff to gas flow into each expansionchamber, such as where it is desired to develop full engine power. Thatis, movement of each primary rotor lobe out of meshing engagement withits associated recess carries the leading outlet port, depending on thedirection of rotation, across the face of cylindrical cavity 17, thusblocking flow through the lead passageway. With the present inventionthe trailing outlet port is positioned so that it remains incommunication with the expansion chamber for extended gas feedthroughout a further arc of rotation until the primary rotor carriesthis outlet port across the face of the cavity 17.

The flow controlmeans further includes a cylindrical valve member 66comprising a hollow cylindrical shell or sleeve mounted both for axialsliding and rotary movement relative to the inner wall of distributorchamber 38. A pair of axially spaced end walls 67, 68 are carried atopposite ends of the valve sleeve. A control shaft '69 mounted on endwall 67 projects outwardly in slidable androtatable sealing relationshipthrough a central opening 71 formed in rotor end plate 43, and a supportshaft 72 mounted on the opposite end wall 68 projects outwardly inslidable and rotatable sealing relationship through a central opening 73formed in output shaft 36. A-control lever 74 or a hinged foot pedal,not shown, is connected for operating the control shaft for axiallysliding movement within the distributor chamber. Suitable means such asthe shaft end pin 76 and slotted frame 77, or straight sliding splines,not shown, is providedjfor restraining the valve sleeve from rotationwith respect to housing 11. A plurality of openings 80 are formed in thetwo sleeve end walls 67, 68 for communicating gas received from inletport 39 both into the interior volume of the valve sleeve and into thevvolume between end wall 68 and the opposed end plate 37 of the primaryrotor. The

pressure of gas is thus evenly distributed on opposite ends of the valvesleeve so that the resultant thrust force acting on the valve sleeve isminimal. This permits the valve sleeve to'be shifted axially in eitherdirection with a relatively small operating force.

Valve sleeve 66 is formed with a pair of flow control ports 78, 79specially adapted to control forward, reverse, braking and throttlingengine functions by means of only one control input, that is throughselection of the axial position for the valve sleeve. The two ports aredefined by openings through the cylindrical wall of the sleeve ataxially spaced-apartp'ositions. The peripheral boundariesv of theopenings include admission edges 81, 82 (FIG. 4) extending parallel tothe primary rotor axis together with cutofi' edges 83, 84-which divergeapart in opposite directions from the admission edges. The remainingsides of the openings are defined by circular edges 86, 87 extendingfrom the outer end of the cutoff edges perpendicular to the outer end ofrespective admission edges. With the valve sleeve developed into animaginary plane, the boundaries of the two control ports wouldsubstantially define right triangles, although the cutoff edges could becurvilinear, as desired. Because the valve sleeve does not turn relativeto the housing, the two admission edgesfor the control ports are fixedin position with respect to a vertical plane passing longitudinallythroughthe two axes about which the rotors turn. Thisconfigurationinitiates the admission of gas into the expansion chambers as theprimary rotor turns through its successive dead-center positions for thethree lobes. This uncovers distributor inlet ports 62 as they move intoregister with the admission edge'of either the forward or reverse port,irrespective of the axial throttling position of the valve sleeve. Withthe control shaft shifted to the position illustrated in FIG. 3 at whichvalve sleeve is in its extreme left-hand position, it will be seen that,with a clockwise rotation of the primary rotor as viewed in FIG. 1,successive distributor passage inlet ports remain in fluid communicationwith the gas distributor chamber throughout a maximum angular sector ofrotation until the inlet ports move over and are occluded by cutoff edge83. Because this cutoff edge diverges from admission edge 82 in an axialdirection, the arc of primary rotor rotation through which thedistributor inlet ports remain in communication is a function of theaxial position of the valve sleeve. Gas flow throttling for powercontrol thereby is varied between engine shutdown, at which the valvesleeve is shifted to a position substantially axially centered withinthe rotor, and the full power position of FIG. 3.

With valve sleeve shifted to an opposite position at the right-hand endof the distributor chamber, as viewed in FIG. 3, braking and reverseport 79 is carried so that it is in register with the successivedistributor inlet ports. The admission edge 81 of port 79 is positionedin fixed relationship with respect to the housing so that with primaryrotor moving counterclockwise, as viewed in FIG. 1, successivedistributor inlet ports 59, 60 are uncovered as they move across theprimary rotor dead-center position. These inlet ports remain influid'communica tion with distributor chamber 38 to direct pressurizedgas into successive expansion chambers 53 up to the point at which theyare occluded by cutoff edge .84. Again, gas flow throttling iscontrolled as a function of axial position of the valve sleeve inthatthe inlet port exposure is a function of the angular sector of travel ofthe distributor passage inlet ports between the admission and cutofi'edges.

Means is formed in housing 11 to utilize the energy of secondaryexpansion of the gas which remains in successive recesses 48 50following disengagement from, the lobes. This means includes secondarypas sages 88, 89 formed on either side of the housing. The passage 88extends from an inlet port 91 opening through the side wall of secondaryrotor cavity 16 to an outlet port92 opening through the side wall ofprimary rotor cavity 17. The opposite secondary passage 89similarlyincludes an inlet port 93 opening into the opposite side wallof secondary rotor cavity 16 and an outlet port 94 opening through theopposite side wall of primary rotor cavity 17. Assuming forward engineoperation, or counterclockwise rotation of the secondary rotor asillustrated in FIG.'2, the residual gas contained within the recess 49which has just disengaged from lobe 21 continues. to expand and act'against primary rotor 18 up to the point that secondary rotor edge 96moves across housing edge 97. Following this the residual gas from therecess expands into secondary passage 89. As outlet port 94 of thispassage is uncovered by the trailing edge 98 of lobe 21 the containedgas discharges into cavity 17 where it acts against the primary rotor.Similarly, in reverse engine operation, with the secondary rotor turningclockwise as viewed in FIG. 2, the residual gas contained withinsuccessive recesses flows through secondary passage 88 and into theopposite side of cavity 17 to act against .the primary rotor. Thissecondary expansion of the residual gasses acts to. increase the powerand efficiency of the rotory engine.

Exhaust means is provided to expel the expanded gasses from the cavityof the primary rotor. This means includes an exhaust chamber 99 formedat the lower end of housing 11 with lateral sides 101, 102 divergingupwardly to the side walls of cavity 17. An exhaust port 103 expellsgasses outwardly from the exhaust chamber, with the engine running ineither forward or reverse directions, as the trailing edges of theprimary rotor lobes move across and uncover the edges 120, 105 of theexhaust chamber side walls. The exhaust port either expells the gasesdirectly to ambient, or through piping, not shown, leading to a suitablecondenser, as where the rotary engine is operated in a closed circuitsystem.

In operation, it will be assumed that rotary engine is employed in aclosed circuit system for operation as a Rankine cycle engine. Theworking fluid employed is steam supplied from a suitable boiler intoinlet port 39 at a temperature of approximately 850F. and a pressure ofapproximately 800 psi. For forward engine operation, i.e., clockwiserotation of primary rotor 18 as viewed in FIG. 1, control shaft 69 isaxially shifted by the control linkage 74 to a position at which theapex between admission edge 82 and cutofi' edge 83 of port 78 registerswith the path of movement of the inlet ports 62 for the distributorpassageways. Where the primary and secondary rotors are in dead-centerposition, i.e., with any one of the primary rotor lobes in an exacttwelve oclock position, initial clockwise motion is imparted to theprimary rotor either through a second pair of primary and secondaryrotors, or through a suitable starting motor coupled to output shaft 36.Steam from inlet port 39 initially flows through distributor chamber 38into the interior of valve sleeve 66. The steam then flows both throughthe opposite sleeve end wall openings 80 for pressure balancing of thesleeve, and through forward control port 78 and the distributorpassageway inlet ports 62 of the first lobe 21. The steam dischargesfrom the two distributor passageways into the expansion chamber 53defined between the outer peripheral surface of the lobe and theopposing root surface of recess 49. With lobe displaced through an arcof travel past its dead-center position the resultant pressure forceswithin the expansion chamber act against the primary rotor eccentric toits axis of rotation, thereby imparting a driving torque to the rotorand output shaft 36. At the same time, the resultant pressure forceswithin the expansion chamber act directly through the axis of rotationof secondary rotor 44 irrespective of its angular position so that nodriving torque is imparted to the secondary rotor.

Rotation of the primary rotor turns drive gear 57 and driven gear 58 torotate secondary rotor 44 in one-toone ratio and in opposite rotationaldirection to synchronize the meshing engagement of the lobes andrecesses. Sealing of the expansion chambers 53 is initially maintainedbetween the lobe outer surfaces and the opposing surfaces of the recess,together with the sealing maintained between opposite end faces of thetwo rotors and the facing housing side walls. As the leading lobe edge104 reaches the housing edge 97 sealing of the expansion chamber ismaintained between the outer surface of lobe 21 and the opposing surfaceof the wall of cavity 17, and between the outer surface 106 of secondaryrotor 44 and the opposing side wall of cavity 16. The trailing portionof the expansion chamber is sealed by the interface between the facingsurfaces of the lobe and recess up to the point of lobe disengagement,afterwhich sealing is maintained by the rolling line of contact betweenthe outer surface 107 of the secondary rotor and the inner cylindricalsealing surface 108 of the primary rotor, as best illustrated in FIG. 2.

Steam continues to be fed into the expansion chamber from the twodistributor passageways 59, 60 until the lobe 21 rotates to a positionat which the outlet port 63 of lead passageway 60 moves across and isoccluded by housing edge 97. Because the trailing passageway 59 iscircumferentially spaced behind the lead passageway the expansionchamber continues to be supplied with steam until the trailing outletport 64 moves across and is occluded by housing edge 97. The provisionof the pair of leading and trailing distributor passageways makes itfeasible to delay cutoff of steam flow for additional power andincreased efficiency, and this is of special importance where the sleevevalve is shifted towards its full power position. I

As illustrated in FIG. 2 the expansion chamber 53 enlarges in volume asthe two rotors turn such that the total volume is a combination of thevolume of recess 49 and the volume within cavity 17 which is sweptbehind lobe 21. When the trailing edge 98 of this lobe moves across anduncovers the outlet port 94 of secondary passage 89, the residual volumeof steam from recess 49 discharges into cavity 17 behind the lobe to actagainst the primary rotor. This secondary expansion permits theutilization of the steam which would otherwise be trapped within therecesses as the recess trailing edges move across the housing edge 97.

To apply increased power to the engine, control shaft 69 is displaced tothe left to carry valve sleeve to a position at which a greater angularsector between control port admission edge 82 and cutoff edge 83 isbrought into register with distributor inlet ports 62. The result isthat the distributor inlet ports are in fluid communication with thesteam within distributor chamber 38 for a greater circular arc ofrotation such that a greater volume of steam is fed into the expansionchambers. At the extreme left hand position of the valve sleeve, asshown in FIG. 3, a maximum angular sector of control port registry isestablished so that full power is developed. As engine speed increasesvalve sleeve may be rotated about its longitudinal axis by suitablespeed responsive governor control means, not shown, connected with shaft69 so that the admission edge 82 is displaced counterclockwise, asviewed in FIG. 1, through a small arc of travel, thereby advancing therate of steam supply into the expansion chambers for increasedefficiency at high speeds.

Expanded steam from the expansion chambers is expelled through exhaustport 103 as the trailing edges 98 of successive lobes move across andseparate from the edge between cavity 17 and the wall of exhaust chamber99. Steam from theexhaust port is either expelled to ambient in an opencircuit system, or is directed through piping into the condensor of aclosed cycle systern.

Where it is desired to brake the forward running engine valve sleeve 66is shifted to the right, as viewed in FIG. 3, so that steam supply intothe expansion chambers is progressively decreased and then terminated asthe annular surface between the two ports 78, 79 registers with thedistributor inlet ports. Further axial shifting of the valve sleeve inthe same direction carries the apex of braking and reverse port 79 intoregister with the distributor ports. This causes steam to be fed intothe contracting volume defined between the successive recesses and lobeswhich are moving into meshing engagement. The pressure of the steamwithin this volume actsagainst and exerts a torque on the primary rotoropposite to the direction of rotation. The volume of steam which isadmitted for braking, and thereforethe magnitude of braking power, is afunction of the anguinlet ports. Operation of the engine in reversedirection is similar to that explained above for forward enginerotation, with the movement of the two rotors being in oppositedirectional senses. In addition, the expansion of residual steam fromthe recesses 48-50 is through the secondary passage 88 which directs thesteam into primary rotor cavity 17 on the opposite side of housing Fromthe foregoing it is apparent that applicants have provided herein a newand improved rotary engine and gas flow control valve specially adaptedfor operation in a Rankine cycle engine. The invention provides theinherent advantages of both Rankine cycle operation and purely rotarymotion for the engine elements.-

Operation of the engine through a'Rankinecycle utilizing a working fluidsuch as steam orFreon vapor is productive of a continously rising torquecurve such that the engine'will not stall-out under heavy load, nor doesit have to be unloaded for restarting. As a consequence the need for acomplex and costly transmission is obviated, and furthermore the engineis adapted for running under high loads atrelatively low rpm. TheRankine cycle operation of the engine further is productive ofrelativelyclean exhaust in that combustion is readily controlled in anexternal combustion chamber with the amount of harmful combustionby-products reduced or eliminated, and in addition relatively low-octanefuels may be efficiently burned. The elements of the rotary engineundergo purely rotary movement so that the relatively high inertialoading and high stresses associated with reciprocating engines isobviated, with'the result that the engine runs smoothly, quietlyandrelatively vi-.

- bration free. There are only two primary moving parts so that theengine is relatively simple and inexpensive in design and operation,with concomitant ease of maintainance and repair. The working fluid usedin the system may be steam or Freon vapor and the like. The use of a gassuch as Freon vapor affords relatively high specific power as a resultof the vapors relatively high density, and this working fluid providesother advantages which include a relatively lower boiling temperature, arelatively low freezing point, lower cycle temperature and pressures,and inherent lubricating properties. The sleeve valve of the engine isadapted for controlling forward and reverse rotational directions,engine braking, and throttling by the control of only one function, thatis through axial shifting of the valve element. "The sleeve valve isinherently balanced so that only relatively small shift forces arerequired to control engine operation. Furthermore, the sleeve valve doesnot rotate with respect to the housing so that it is not stressed byinertial forces from reciprocating parts, as compared to slide, pistonand poppet valve arrangements.

We claim:

1. In a valve for controlling the flow of gas from a source of gas underpressure to an engine having a gas expansion phase in its operativecycle for producing mechanical work, the combination of means forming acylindrical chamber having an inlet in fluid communication with saidengine, means forrning a distributor passageway in fluid communicationwith said engine, a cylindrical valve member mounted for axial slidingmovement within said chamber, means forming at least one flow controlport in said valve member, means mounting said distributor passagewaymeans for rotation about said valve member responsive to cycling of saidengine, said flow control port being bounded about its periphery by anaxially extending admission edge and a cutoff edge, said cutoff edgediverging from said admission edge along the outer periphery of saidvalve member, means forming a second flow control port in said valvemember axially spaced from said first mentioned port, said second portbeing bounded about its periphery by a second admission edgesubstantially axially aligned with said first mentioned admission edgetogether with a second cutoff edge diverging from said second admissionedge in a direction opposite of said first mentioned cutoff edge wherebyaxial movement of said valve member selectively moves either of saidflow control ports into register with said distributor passageway meansfor forward or reverse cycling of said engine, and means to selectivelymove said valve member in an axial direction within said chamber to varythe angular sector between said admission and cutoff edges whichregisters with said distributor passageway means during each enginecycle.

2. A rotary engine to produce mechanical work from a source of gas underpressure, including the combination of a housing, a primary rotor of agiven diameter mounted for rotation within said housing about a firstaxis, a plurality of circumferencially spaced, radially outwardlyprojecting lobes being formed on said primary rotor, a second rotor of adiameter different than said given diameter mounted for rotation withinsaid housing about a second axis parallel with and spaced from saidfirst axis, a plurality of circumferencially spaced, radially inwardlyprojecting recesses being formed on said secondary rotor, said recessesbeing sized for meshing engagement with respective ones of said primaryrotor lobes to define successive expansion chambers therewith, flowcontrol means to direct gas from said gas source through said primaryrotor and into successive expansion chambers whereby the resultantpressure force of the gas therein acts eccentrically upon said primaryrotor to turn the same about said first axis, said flow control meansincluding means forming a distributor chamber within said primary rotorradially inward of said lobes and in fluid comminication with saidsource of gas under pressure, means forming a plurality of distributorpassageways within said primary rotor and extending substantiallyradially outwardly through said lobes, each distributor passagewayincluding an inlet port positioned to register in communication withsaid distributor chamber and further including an outlet port positionedat the outer periphery of respective lobes to direct gas into saidexpansion chambers, said flow control means further including valvemeans to selectively control the volume of said gas flowing from saiddistributor chamber into said distributor passageways, said valve meanscomprising a cylindrical valve member mounted within said distributorchamber for relative rotationalmovement with respect to said primaryrotor, means forming a pair of flow control ports at axial spacedpositions on said valve member, each of said control ports being influid communication with said distributor chamber and being boundedabout its periphery by at least one axially extending admission edgepositioned to establish communication from said distributor chamber tosaid distributor passageway inlet ports when successive secondary rotorrecesses are in meshing engagement with respective primary rotor lobes,each of said ports further being bounded about their peripheries bycutoff edges which diverge from their associated admission edges inopposite directions whereby registry of said control ports with saiddistributor inlet ports is effective to direct said gas into successiveexpansion chambers for respective forward and reverse rotation of saidprimary rotor, and means to move said valve member axially along saidfirst axis to selectively move said control ports into and out ofregister with the inlet ports of said distributor passageways.

1. In a valve for controlling the flow of gas from a source of gas underpressure to an engine having a gas expansion phase in its operativecycle for producing mechanical work, the combination of means forming acylindrical chamber having an inlet in fluid communication with saidengine, means forming a distributor passageway in fluid communicationwith said engine, a cylindrical valve member mounted for axial slidingmovement within said chamber, means forming at least one flow controlport in said valve member, means mounting said distributor passagewaymeans for rotation about said valve member responsive to cycling of saidengine, said flow control port being bounded about its periphery by anaxially extending admission edge and a cutoff edge, said cutoff edgediverging from said admission edge along the outer periphery of saidvalve member, means forming a second flow control port in said valvemember axially spaced from said first mentioned port, said second portbeing bounded about its periphery by a second admission edgesubstantially axially aligned with said first mentioned admission edgetogether with a second cutoff edge diverging from said second admissionedge in a direction opposite of said first mentioned cutoff edge wherebyaxial movement of said valve member selectively moves either of saidflow control ports into register with said distributor passageway meansfor forward or reverse cycling of said engine, and means to selectivelymove said valve member in an axial direction within said chamber to varythe angular sector between said admission and cutoff edges whichregisters with said distributor passageway means during each enginecycle.
 2. A rotary engine to produce mechanical work from a source ofgas under pressure, including the combination of a housing, a primaryrotor of a given diameter mounted for rotation within said housing abouta first axis, a plurality of circumferencially spaced, radiallyoutwardly projecting lobes being formed on said primary rotor, a secondrotor of a diameter Different than said given diameter mounted forrotation within said housing about a second axis parallel with andspaced from said first axis, a plurality of circumferencially spaced,radially inwardly projecting recesses being formed on said secondaryrotor, said recesses being sized for meshing engagement with respectiveones of said primary rotor lobes to define successive expansion chamberstherewith, flow control means to direct gas from said gas source throughsaid primary rotor and into successive expansion chambers whereby theresultant pressure force of the gas therein acts eccentrically upon saidprimary rotor to turn the same about said first axis, said flow controlmeans including means forming a distributor chamber within said primaryrotor radially inward of said lobes and in fluid comminication with saidsource of gas under pressure, means forming a plurality of distributorpassageways within said primary rotor and extending substantiallyradially outwardly through said lobes, each distributor passagewayincluding an inlet port positioned to register in communication withsaid distributor chamber and further including an outlet port positionedat the outer periphery of respective lobes to direct gas into saidexpansion chambers, said flow control means further including valvemeans to selectively control the volume of said gas flowing from saiddistributor chamber into said distributor passageways, said valve meanscomprising a cylindrical valve member mounted within said distributorchamber for relative rotational movement with respect to said primaryrotor, means forming a pair of flow control ports at axial spacedpositions on said valve member, each of said control ports being influid communication with said distributor chamber and being boundedabout its periphery by at least one axially extending admission edgepositioned to establish communication from said distributor chamber tosaid distributor passageway inlet ports when successive secondary rotorrecesses are in meshing engagement with respective primary rotor lobes,each of said ports further being bounded about their peripheries bycutoff edges which diverge from their associated admission edges inopposite directions whereby registry of said control ports with saiddistributor inlet ports is effective to direct said gas into successiveexpansion chambers for respective forward and reverse rotation of saidprimary rotor, and means to move said valve member axially along saidfirst axis to selectively move said control ports into and out ofregister with the inlet ports of said distributor passageways.